Compressor



Nov. 20, 1928.

1,692,268 H. B. HALVORSEN COMPRESSOR Filed April 25, 1926 2 Sheets-Sheet 1 gaZieriflfia/Zwmem A; A- M.

Patented Nov. 20, 1928.

UNITED STATES PATENT GFFICE- HALBERT B. HALVORSEN, OF MICHIGAN CITY, INDIANA, ASSIGNOR TO SULLIVAN MACHINERY COMPANY, A CORPORATION OF MASSACHUSETTS.

COMPRESSOR.

Application filed April 26, 1926. Serial No 104,745.

This invention relates to compressors, and more particularly to unloading systems for compressors. h

In many compress or installationsit is found that intermittent driving of the compressor best meets the compressed fluid demand and in such installations it is customary to provide a compressor with an automatically controlled driving motor which begins to drive the compressor when the pressure of the compressed fluid falls to a predetermined minimum and which stops and so discontinues compressor drive when a somewhat higher predetermined desired maximum pressure is obtained. In such systems it is desirable to have the compressor started unloaded and in the case of compound compressors it ohviously is best that the high aswell as the low pressure cylinder be unloaded.

Among the objects of the present invention is the provision of improved unloading mechanism for a compound compressor. An-

other object is to provide improved unloading means controlled by the lubricating system of the compressor. A more specific object is to provide improved unloadin means for a compound compressor which will automatically unload each stage thereof during starting and while coming substantially up to speed. Other objects and advantages of the invention will subsequently appear.

In the accompanying drawings, in which for purposes of illustration one embodiment which the invention may assume in practice is shown:

Fig. 1 is a side elevation of a compressor equipped with the illustrative embodiment of my invention.

Fig. 2 is an end elevation of such a compressor with certain parts shown in vertical section on the line 22 of Fig. 1.

Fig. 3 is an enlarged detail vertical sectional view through a portion of the high pressure cylinder unloading mechanismi Fig. i is an enlarged detail sectional view of a check valve construction.

Fig. is a section on the line 55 of Fig. 3.

While the invention may obviously be embodied in other systems and with other types of pumping apparatus, it is shown herein embodied in an angle compound compressor system. In this system a compressor 1 comprises a low pressure cylinder 2 and a high pressure cylinder 3... The low pressure cylinder discharges through a connection 4 into an intercooler 5. The intercooler 5 is connected to the suction side of the high pressure cylinder 3. through a line 6. The crank shaft 7 of the compressor may be driven in any suitable manner.

Connected to the crank shaft 7 by a link 8 is an oil pump 9 whose suction side is con nected to the crank pit or oil sump of the compressor 1. The pump 9 discharges oil through a check valve 10 to a line 11. The line 11 branches at a T 12 and one branch 13 leads to high pressure cylinder unloading mechanism later described. Another branch 14 leads into the cross 15 to whose lower arm a drain valve 16 is connected. The upper arm of the cross 15 is connected through a special check valve 17 to a stand pipe 18 of wellknown construction, and suitable lubricant supply connections, not shown, lead oii' from this stand pipe. An excess supply of oil to the stand pipe is returned to the sump through a concentric overflow line 19. The fourth branch of the cross 15 receives a line 20 which' opens through a manually controllable stop valve 21 into a T 22 whose lower branch is closed by a plug 23 which may be removed for drainage purposes as later described. The upper branch of the T 22 connects through a pipe 23 with the lower ends ofa pair of parallelspaced cylinders 24:. The cylinders 24 are mounted upon thecover of an intake closure type unloading valve 25 which cooperates with ports 26to close the intake and thereby unload the compressor. 1 Within the cylinders 24 are pistons 27 having vertically extending piston rods 28 connected by a cross arm or yoke 29. A stem 30 carried by the yoke 29 sup-.

ports a weight 31 movable between the cylinders 24 and resting upon a nut 33. Below the nut 33 a second nut 35 is mounted and the portion of the rod 30 between the nuts passes through an opening 36 in the middle of the valve 25, the nuts 33 and 35 being spaced by a somewhat greater distance than the length ol the opening 36 in the valve 25 for a reason which will subsequently appear. The connection between the pipe 23 and the cylinders 2 1 may assume various forms, but in all cases the pressures in the cylinders will be desirably equalized. The

spaces above the pistons 2"? are connected by a cross channel to which is connected a pipe 38 which conducts any oil which may leak past the pistons into the frame where it flows to the crank pit.

The check valve 17 comprises a casing 4:0 dividedby a septum 1-1 into chambers 42 and 43 respectively connected to the cross and to the stand pipe 18. The septum is traversed by an opening l i with which the valve 45 cooperates. A spring l6 normally maintains the valve closed and may be subjected to adjustable pressure if desired. A set screw 47 held in different adjusted positions by a 'lock nut d8 prevents the complete closure of the valve 45 and accordingly permits leakage of 011 through the check valve when the pump 1s not running.

The spring loaded check valve 17 is interposed between the oil pump 9 and the stand pipe 18 in order to create sufficient pressure to overcome the weight of the low pressure unloading valve 25, weight 31, and attached parts. By adjusting the set screw 47 the valve 15 is raised from its seat as explained above, leaving a small opening through which oil from the cylinders 24 will escape into the stand pipe 18 when the compressor stops and the oil pump is not working. The weightBl is therefore made heavy enough to overcome the head of oil in the stand pipe 18 and bring the pistons in cylinders 24 to thebottom. The structure so tl'ar described is in many particulars similar to the unloading mechanism described and claimed in the copending application of Wade H. ineman, Faerial No. 259,788, filed October 26, 1918, which issued Patent 1,602,? 91, on Oct. 12, 1926, but in certain details differs from that mechanism. The mode of operation of the low pressure unloading mechanism may be brieflydescribed before taking up the structure of the high pressure cylinder unloading mecha nism.

Assuming that the compressor in starting, the oil pump will deliver oil in increasing quantities as thecompressor driving motor gains speed. The pressure of the spring l6 on the check valve l5 is adjusted so that the oil will not pass freely into the stand pipe 18 until the pressure of the oil in line is sulficient to raise the pistons 27 It may take from ten to fifteen seconds for the motor to reach full or pull in speed (the preferable speed for putting the load on the motor), and the proportioning of the parts, and the amount of leakage past the check valve is suli'icient so that the upward movement of the pistons 27 does not bring the lower nut 35 into contact with the valve 25 and unseat the latter until after the driving motor reaches its normal speed. This proportioning of the parts is obviously governed by the displacement volume of the two cylinders 2e and of the pistons, allowance being made for leakage past the check valve 15 and the pistons. As synchronous speed is reached in the case of a synchronous electric driving motor or the normal running speed in the case of an internal combustion engine, or other types of electric motors, the volume of oil pumped will. be increased owing to the increased speed of the pump and the unloading valve 25 will be promptly raised from its seat and held wide open as long as the compressor is running. After shut down, the valve will be closed by the weight 31 in addition to its own weight and the weight of the pistons; and the oil in the cylinders 24 will be drained back through theslight opening past the check valve l5. By means of the stop cock 21 the oil may be shut oil from the cylinders 24 and the oil drained oil by the removal of the plug 23 in theT 22 when it is desired to examine or adjustthe low pressure cylinder intake closure mechanism.

For thepurpose of venting the intercooler and avoiding the necessity for starting the compressor against substantially full load in the high pressure cylinder the opposite ends of the high pressure cylinder are provided with check valves 51 and '52 which may be of any suitable form, but are herein shown as ball check valves connected by short pipe sections 53 with the clearance volumes at either end of the high pressure cylinders. Each of the valves 51 and 52 comprises a casing 54; whose interior is divided into two chambers by a septum 05,, the septum being traversed by an opening 56 upon which a ball check valve 57 seats. The bottoms of the valve casings 54 are provided with openings 58 through which stems 58" extend into a position to engage with the check valves 57 and unseat the latter. During the load ed running of the compressor the upper ends out the stems 58 are spaced a shortdistance below the valves 57 to insure the complete closure of the latter. The two stems are joined together by a yoke 59 having arms 60 arranged at opposite sides of the lower check valve device 52. Any suitable means may be provided to permit relative adj ustment o'lithe stems -58. For example, the stem 58 of the upper valve may be held by adjustable nuts 61 to the upper end of the yoke 59 while adjusting mechanism 62 may be arranged to cooperate with the stem 58 of the lower valve. The yoke 59 is pivotally connected at 63 to a lever 6a which is mounted upon a link 65 and connected at 66 to a vertically reciprocable rod 6'4" Hill which engages at its lower end ahead 68 resting upona suitable flexible diaphragm 69. The diaphragm 69 forms the upper bounding wall of a chamber 70 formed in the casing 71 and the chamber 70 communicates through an Opening 72 with the pipe 13, previously de scribed. A spring 73 normally acts to hold the lever arm 64 in a position to raise the valve stems 58 and accordingly to hold the check valves 57 off their seats. By reason of the connections described, the lower part of the diaphragm. chamber 70 is subjected to the same pressure variations as occur in the cylinders 24.

The mode of operation of this portion of the mechanism may now be briefly noted. hen the compressor has been idle for some time there will be no pressure underneath the diaphragm 69 and the spring 7 3 will therefore cause opening of the check valves 51 and 52, allowing the confined air to escape. These valves will remain open until, after the starting of the compressor, a. sufficient oil pressure is built up in the chamber 70 to overcome the tension of the spring 73and move the lever 64 upward to a suflicient extent to permit seating of the check valves 57. The parts are proportioned so that when the low pressure unloading valve is about to open, the pressure beneath the diaphragm 69 will overcome the spring tension and allow the check valves to close.

From what has been said it will be obvious that my improved compressor unloading system provides for the simultaneous loading of the high and low pressure cylinders and does not require any manual unloading of the high pressure cylinder or permit the imposition upon the compressor driving motor while the latter is coming up to speed of the burden of pumping the intercooler pressure into the dis charge line against the pressure in the latter. The check valves 51 and 52 may obviously be arranged in different places either in the intake connection of the high pressure cylinder or in the discharge lines and maybe controlled if desired automatically in other methods and by different mechanisms from those described.

While I have in this applicationspecifically described one form which my invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustration and that the invention may be modified and embodied in various other forms without departing from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is 1. In a compressor system comprising a multi-stage compressor, unloading means for a low pressure stage, unloading means for a high pressure stage, a lubricating system, and means connected to the lubricating system for controlling said unloading means, said seeond mentioned unloading means including a plurality of relief means and a unitary actuator for said relief means.

2. In a compressor system comprising a sion, cylinder relief means for another stage of compression, and means for controlling said intake controlling valve and cylinder relief means comprising means, other than the multi-stage compressor, for generating a fluid pressure.

4. In a muti-st-age compressor, the combi nation comprising a normally closed valve controlling the intake to one stage of compression, cylinder relief means for another stage of'compression, and means for controlling said intake controlling valve and cylin der relief means comprising means, other than the multi-stage compressor, for generating a fluid pressure and for permitting said pressure to fall when said pressure generating means ceases to function.

5. In a multi-stage compressor, the combination comprising normally closed valve means for controlling the intake to one stage of compression, and cylinder relief valve means for another stage of compression, fluid pressure means for opening said first mentioned valve means and permitting said second mentioned valve means to close, and means including a non-seating, constantly partially open valve for controlling said fluid pressure and for permitting said second mentioned valve means to close.

6. In a multistage compressor, the combination comprising a lubricating system, means for producing lubricant flow therein. under pressure, a valve means adapted upon opening to load or upon closing to unloadone stage of said compressor, a valve means adapted upon. closing to load or upon opening to unload another stage of said compressor, and means governed and operated by the lubricant pressure for moving both of said valve means.

7. In a compressor system, in combination, driving means, a compound compressor driven thereby, an intake unloader for said compressor, unloading means for a stage above the first fluid pressure motor means controlling said unloading devices, and liquid pressure generating means supplying til to said motor means and driven by said driving means, said motor means being of the expansible chamber type and comprising relatively movable chamoer forming elements a predetermined relative movement of which controls loading movements of said unloading mechanisms, the increase in volume in said motor means durpressure ing such relative movement bearing a predetermined relation to the capacity of the liquid pressure generating means during the time required for said driving means to bring said compressor up to speed.

In testimony whereof I afix my signature.

HALBERT B. HALVORSEN.

CERTIFICATE OF CORRECTION.

Patent No. 1,692,268. Granted November 20, 1928, to

HALBERT B. HALVORSEN.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 2, line 54, for the word "in" read "is"; page 3, line 81, claim 3, after the word "compressor" in sert a comma, and line 128, claim 7, after the Word "first" insert a comma; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office,

Signed and sealed this 19th day of February, A, D. 1929i 7 M. J. Moore, (Seal) Acting Commissioner of Patents. 

